Loma IQ2 User Manual page 132

115
Installing the metal
detector
into the aperture must also be non metallic. Use Darvic or some similar material and keep the
mounting posts out of the metal free area.
Moving metal
Moving metal must be sited at least three times the smaller of the two aperture dimensions
from the centre of the head, as illustrated in Further information, page 118. Moving metal
includes rollers whether idler, drive or end rollers. This requirement determines the minimum
length of the conveyor, eg for a 300mm smaller dimension aperture, assuming the head is
sited in the middle, the minimum conveyor length has to be 1.8m to ensure that the end
rollers are out of the moving metal free area.If rollers cause false triggering when rotating, try
insulating one end to open circuit a possible eddy current loop. Other moving metal could
include supply cables or conduits draped across or to one side of the conveyor and not
rigidly fixed.
Vibration
It is important that the head is not subjected to excessive vibration. Thus the conveyor on
which the head is mounted must be substantial and well supported to keep the head stable.
Electrical services to the head must be taken up in a flexible not rigid conduit.
NOTE: Do not use the head or control box as a convenient point to anchor any conduit or
pipe work whatever, whether it be rigid or flexible.
NOTE: Do not use the head as a walkway across the conveyor or as a convenient writing
desk or repository for odds and ends.
Belting
The conveyor belt should be of a plastic or polyurethane type with an angled belt join,
preferably at 60˚, but no more than 75˚, and be vulcanised or heat sealed. A 90˚ lap, clipped
or sewn joint is not acceptable as product can get picked up in the joint and the detector will
have to be run at reduced sensitivity to avoid false triggering.
Some belts, particularly slatted types, use oxide pigments as a colouring material. These are
metallic in origin and can cause false triggering, particularly at the belt joint where the oxides
are concentrated. These should be avoided.
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